Pneumatic tire

a technology of pneumatic tires and tires, applied in the field of pneumatic tires, can solve the problems of deteriorating steering stability on dry road surfaces

US20160144668A1Active Publication Date: 2016-05-26SUMITOMO RUBBER IND LTD
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2016-05-26

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Abstract

To provide a pneumatic tire which is improved in on-snow performance, while maintaining steering stability on dry road surface. The pneumatic tire is provided in a tread portion 2 with a pair of shoulder main grooves 3, a center main groove 4, shoulder land portions 6, and middle land portions 5. The middle land portions 5 are provided with middle lateral grooves 10 extending from the shoulder main grooves 3 toward the inside in the tire axial direction, while gradually decreasing the angle with respect to tire circumferential direction. The middle lateral groove 10 is provided with a groove bottom sipe 15 opened in the groove bottom.
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Description

TECHNICAL FIELD

[0001] The present invention relates to a pneumatic tire which is improved in on-snow performance, while maintaining steering stability on dry road surface,BACKGROUND ART

[0002] There has been proposed a pneumatic tire provided in the tread portion with sipes and lateral grooves extending in the tire axial direction.Such pneumatic tire is improved in running performance on snow (hereinafter, referred to as “on-snow performance”) by edge components of the lateral grooves and the sipes.

[0003] The lateral grooves and sipes as described above, however, reduce the rigidity of the tread portion, and there is a problem of such that the steering stability on dry road surface is deteriorated.

[0004] In the following Patent Document 1, there has been proposed a pneumatic tire in which the inclination direction of belt cords of a belt ply, and the inclination direction of lateral grooves in the tread portion are defined in order to suppress a decrease in the rigidity of the tread port...

Examples

working example

[0085]Pneumatic tires of size 185 / 60R15 having the basic pattern shown in FIG. 1 were experimentally manufactured based on the specifications shown in Table 1.

As a comparative example, a pneumatic tire not having a groove bottom sipe was experimentally manufactured.

Each test tire was tested for the steering stability on dry road surface and on-snow performance.

[0086]Common specifications to all of the tires and test methods are as follows.

[0087]mounting rim: 15×63

[0088]tire inner pressure: 230 kPa

[0089]test vehicle: front-wheel-drive vehicle,[0090]engine displacement 1300 cc

[0091]tire mounting position: all wheels

[0092]The steering stability when the test vehicle was traveling on a test course constituted by a dry asphalt road was evaluated by driver's sense.

The result is a grade based on comparative example 1 being 100, wherein the larger the number, the better the steering stability.

[0093]The on-snow performance when the test vehicle was traveling on snow was evaluated by driver's...